Trifluorotoluene

Trifluorotoluene
Names
	Other names Benzotrifluoride (BTF); α,α,α-Trifluorotoluene ; CF3Ph; PhCF3
Identifiers
CAS Number	98-08-8 ;
3D model (JSmol)	Interactive image;
ChemSpider	7090;
ECHA InfoCard	100.002.396
EC Number	202-635-0;
PubChem CID	7368;
UNII	49R6421K89 ;
CompTox Dashboard (EPA)	DTXSID2024589 ;
	InChI InChI=1S/C7H5F3/c8-7(9,10)6-4-2-1-3-5-6/h1-5H Key: GETTZEONDQJALK-UHFFFAOYSA-N;
	SMILES C1=CC=C(C=C1)C(F)(F)F;
Properties
Chemical formula	C6H5CF3
Molar mass	146.11 g/mol
Appearance	colorless liquid
Odor	aromatic
Density	1.19 g/mL at 20 °C
Melting point	−29.05 °C (−20.29 °F; 244.10 K)
Boiling point	103.46 °C (218.23 °F; 376.61 K)
Solubility in water	<0.1 g/100 mL at 21 ºC
Solubility	soluble in ether, benzene, ethanol, acetone ; miscible in n-heptane, CCl4
Refractive index (nD)	1.41486 (13 °C)
Hazards
NFPA 704 (fire diamond)	3 0 0
Flash point	12 °C (54 °F; 285 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Trifluorotoluene is an organic compound with the formula of C₆H₅CF₃. This colorless fluorocarbon is used as a specialty solvent in organic synthesis and an intermediate in the production of pesticides and pharmaceuticals.[1]

Synthesis

For small-scale laboratory preparations, trifluorotoluene is synthesized by coupling an aromatic halide and trifluoromethyl iodide in the presence of a copper catalyst:[2]

PhX + CF₃I → PhCF₃ (where X = I, Br)

Industrial production is done by reacting benzotrichloride with hydrogen fluoride in a pressurized reactor.[3]

PhCCl₃ + 3 HF → PhCF₃ + 3 HCl

Uses

Trifluorotoluene has a variety of niche uses.

Low toxicity alternative to dichloromethane

According to Ogawa and Curran, trifluorotoluene is similar to dichloromethane in standard acylation, tosylation, and silylation reactions.[4] The dielectric constants for dichloromethane and trifluorotoluene are 9.04 and 9.18, respectively, indicating similar solvating properties. Dipole moments compare less favorably: 1.89 and 2.86 D for dichloromethane and trifluorotoluene, respectively. Replacing dichloromethane is advantageous when conditions require higher boiling solvents since trifluorotoluene boils 62 °C higher than dichloromethane (b.p. 40 °C).

As a solvent, trifluorotoluene is useful in mild Lewis-acid catalyzed reactions, such as the Friedel-Crafts preparations. The most common catalyst, aluminium trichloride reacts with trifluorotoluene at room temperature; however, zinc chloride does not.

Synthetic intermediate

A second and perhaps more valuable use of trifluorotoluene is as a synthetic intermediate. A derivative of trifluorotoluene, 3-aminobenzotrifluoride, is the precursor to the herbicide fluometuron.[3] It is synthesized via nitration followed by reduction to meta-H₂NC₆H₄CF₃. This aniline is then converted to the urea.

Flumetramide (6-[4-(trifluoromethyl)phenyl]morpholin-3-one), a skeletal muscle relaxant, is also prepared from trifluorotoluene.[1]

Analytics

Trifluorotoluene appears in ¹⁹F NMR as a singlet at -63.2 ppm.[5]

References

Banks, R.E. Organofluorine Chemicals and their Industrial Applications, Ellis Horwood LTD, Chichester, 1979.
Ogawa, Akiya; Tsuchii, Kaname "α,α,α-Trifluorotoluene" in Encyclopedia of Reagents for Organic Synthesis 2005, John Wiley and Sons. doi: 10.1002/047084289X.rn00653
Siegemund, Günter "Aromatic Compounds with Fluorinated Side-Chains" in Ullmann’s Encyclopedia of Industrial Chemistry 2005, Wiley-VCH. doi:10.1002/14356007.a11_349.
Ogawa, Akiya; Curran, Dennis P. (1997). "Benzotrifluoride: A Useful Alternative Solvent for Organic Reactions Currently Conducted in Dichloromethane and Related Solvents". Journal of Organic Chemistry. 62 (3): 450–451. doi:10.1021/jo9620324.
Denmark, Scott E.; Smith, Russell C. (3 February 2010). "Mechanistic Duality in Palladium-Catalyzed Cross-Coupling Reactions of Aryldimethylsilanolates. Intermediacy of an 8-Si-4 Arylpalladium(II) Silanolate (Supplementary Material, referenced as PhCF₃)". Journal of the American Chemical Society. 132 (4): 1243–1245. doi:10.1021/ja907049y. PMC 2812642. PMID 20058920.

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[Banks-1] Banks, R.E. Organofluorine Chemicals and their Industrial Applications, Ellis Horwood LTD, Chichester, 1979.

[2] Ogawa, Akiya; Tsuchii, Kaname "α,α,α-Trifluorotoluene" in Encyclopedia of Reagents for Organic Synthesis 2005, John Wiley and Sons. doi: 10.1002/047084289X.rn00653

[Ullmann-3] Siegemund, Günter "Aromatic Compounds with Fluorinated Side-Chains" in Ullmann’s Encyclopedia of Industrial Chemistry 2005, Wiley-VCH. doi:10.1002/14356007.a11_349.

[4] Ogawa, Akiya; Curran, Dennis P. (1997). "Benzotrifluoride: A Useful Alternative Solvent for Organic Reactions Currently Conducted in Dichloromethane and Related Solvents". Journal of Organic Chemistry. 62 (3): 450–451. doi:10.1021/jo9620324.

[5] Denmark, Scott E.; Smith, Russell C. (3 February 2010). "Mechanistic Duality in Palladium-Catalyzed Cross-Coupling Reactions of Aryldimethylsilanolates. Intermediacy of an 8-Si-4 Arylpalladium(II) Silanolate (Supplementary Material, referenced as PhCF₃)". Journal of the American Chemical Society. 132 (4): 1243–1245. doi:10.1021/ja907049y. PMC 2812642. PMID 20058920.